The overarching goal of this project is to examine the association between borderline personality disorder (BPD) and a) substance use/substance use disorder and b) sexual risk taking/adverse reproductive outcomes (STDs/HIV;unplanned pregnancies) in women. The main factor hypothesized to mediate these associations is neurocognitive competence, specifically executive cognitive function (ECF) capacity, and its hypothesized overt manifestation, risk judgment. The sample will consist of 500 psychiatric outpatients: 300 women with BPD and 200 women without BPD. It will include 200 low-income African-American women who are at particular risk for both substance use and sexual risk taking. Tests of the specific aims will demonstrate that: 1) Severity of BPD covaries with substance use and risky sex beyond the variance accounted for by co-occurring personality disorders and major depression;2) ECF capacity mediates the association between BPD and judgment of risk associated with substance use and risky sex;3) Risk judgment mediates the association between ECF and substance use and risky sex;4) Low judgment of risk associated with substance use moderates (strengthens) the effect of substance use on risky sex, and, low judgment of risk associated with risky sex moderates (strengthens) the effect of risky sex on substance use;5) There is a bi-directional, not merely correlational, association between substance use and risky sex on a) substance use disorder and b) adverse reproductive outcomes. This is the first project to conjointly relate BPD to substance use/risky sex and substance use disorder/adverse reproductive outcomes, to utilize item response theory methods for delineating the relation between personality traits and health risk behaviors, and to determine the impact of ECF and risk judgment on substance use and sexual risk behavior in women with BPD. Modeling the association between BPD, substance use, and sexual risk taking in relation to substance use disorder and adverse reproductive outcomes will inform public health initiatives by documenting the importance of individual differences in a high-risk population (e.g., the need to screen for the presence of BPD in women presenting to substance use treatment programs). By testing both direct and mediated associations between BPD, health risk behaviors and adverse clinical outcomes, this project will be heuristic for devising novel interventions.